Automatic multiple unit control apparatus

ABSTRACT

Control apparatus for automatically enabling and disabling the thermostatic control of a plurality of building temperature control units. A programmable timer is provided for adapting the control apparatus to a desired building use schedule. A manually operable override switch is also provided to allow for temperature control during unscheduled building occupancies and additional circuitry automatically disables the override switch to prevent the control apparatus from remaining overridden for an extended period of time in the event the override switch is not reset. A temperature limit switch is further provided to return the temperature control units to thermostatic control if the building temperature drifts outside a predetermined range during periods of disablement.

This invention relates in general to automatic control apparatus and, inparticular to energy conserving control apparatus for use with buildingtemperature control units such as air conditioning and/or heating units.

Many large commercial and industrial buildings are occupied only parttime and on a regular schedule. For example, a department store may beopen 10 a.m. to 9 p.m. 5 days a week, from 10 a.m. to 6 p.m. on the 6thday, and closed on the 7th day. Such buildings are typically of a sizeto require a plurality of thermostatically controlled heating and/or airconditioning units for maintaining the building temperature at asuitable level for human comfort during periods of occupancy. Foreconomic reasons it is desirable during unoccupied periods to decontrolthe temperature control units to a certain extent. In many instances thetemperature control units cannot be completely decontrolled, however, inorder to prevent possible inventory or building damage such as, forexample, the freezing and subsequent bursting of water lines.

It is, therefore, a principal object of this invention to provideprogrammable control apparatus for a plurality of temperature controlunits that automatically switch from a thermostatically controlled stateduring scheduled periods of occupancy, to a partially decontrolled stateduring unoccupied periods.

It is a further object to provide a manual override capability in theevent of an unscheduled occupancy.

A still further object is to provide circuitry for automaticallydisabling the override capability after a predetermined time to preventthe control apparatus from being overridden for several days at a time.

Another object is to provide for a staggered turn-on of a plurality oftemperature control units so as to prevent a power surge which mightcause a power overload failure.

It is still another object to provide a fail-safe control system whichreturns the temperature control units to individual thermostatic controlin the event of a control system malfunction.

Features of the invention useful in accomplishing the above objectsinclude a programmable timer for switching the temperature control unitsbetween a thermostatically controlled state during periods of buildingoccupancy and an extreme temperature limit switch controlled stateduring unoccupied periods. A plurality of chain-connected time delayrelays are sequentially enabled to provide for a staggered turn-on orturn-off of the temperature control units in response to the state ofthe timer. The contacts of these relays are arranged in a "normallyclosed" configuration in series with the individual thermostats of thetemperature control units so that fail-safe operation is insured. Amanual override switch allows for unscheduled thermostatic control ofthe temperature control units and circuitry is provided to automaticallydisable the override switch whenever the timer automatically switchesthe system to the thermostatically controlled state.

A specific illustrative embodiment representing what is presentlyregarded as the best mode of carrying out the invention is illustratedin the single accompanying drawing figure which depicts a schematicdiagram of circuitry embodying the principles of this invention forcontrolling the operation of a plurality of temperature control units inaccordance with the foregoing objects and features.

Referring to the drawing:

For purposes of illustration, control apparatus 100 is shown connectedbetween a source of 115 volt 60 cycle AC and nine temperature controlunits. The temperature control units may be heaters and/or airconditioners, the connections thereto actually being made in series withthe control lines from the individual thermostats to the respectivetemperature control units. These connections are made through normallyclosed contact pairs of time delay relays 10, 20 and 30 as typicallydepicted in the drawing for a temperature control unit 9A and associatedthermostat 9B through normally closed contact pair 35 of time delayrelay 30. Therefore, in the event of a malfunction of control apparatus100, temperature control units 1 through 9 would remain under, or revertto, the control of their respective thermostats. It is expresslyunderstood that nine temperature control unit connections have beenshown for illustrative purposes only. The exemplary embodiment may beexpanded to control many more units or reduced to control fewer.Additionally, the principles of this invention allow for the exemplaryembodiment to be modified to control such other functions as lighting,factory machinery, etc., without departing from the spirit and scope ofthe invention.

Transformer 40 converts the 115 volt 60 cycle AC from a standard walloutlet into 24 volt 60 cycle AC for operating the relays in controlapparatus 100. Other voltages and frequencies may be utilized in theevent it is so desired. The line voltage is applied directly to motor 51of timer 50. Timer 50 is a programmable timer and may be of the 7 day or24 hour variety. Such a timer typically comprises a contact 52 which isrotated by motor 51. ON contact 53 and OFF contact 54 may be programmedto be alternately engaged with contact 52 during predetermined periodsof the 7 day or 24 hour period. Programmable timer 50 may be of anycommercially available variety that satisfies the requirements of anyparticular application of this invention.

When motor 51 moves contact 52 into engagement with ON contact 53,temperature control units 1 through 9 are removed from the control oftheir respective thermostats as follows. Twenty-four volts is applied toheaters 11 and 12 of time delay relay 10 over the path comprisingcontacts 52 and 53 of timer 50 and normally closed contact pair 61 ofrelay 60. Time delay relays 10, 20 and 30 may illustratively be of thetype manufactured by Texas Instruments and known by the name KLIXON.Other bistable devices with suitable delays, such as solid state delayflip-flops may be substituted for the time delay relays if the specificapplication permits. After a suitable time delay, normally closedcontact pairs 13,14 and 15 open the series connections of temperaturecontrol units 1,2 and 3, respectively, with their respectivethermostats. At this same time, normally open contact pair 16 is closed.This completes a path for heaters 21 and 22 of time delay relay 20 tothe 24 volt supply. After a delay period, normally closed contact pairs23, 24 and 25 open the series connections of temperature control units4,5 and 6, respectively, with their respective thermostats. At this sametime, normally open contact pair 26 is closed. This completes a path forheaters 31 and 32 of time delay relay 30 to the 24 volt supply. After adelay period, normally closed contact pairs 33, 34 and 35 open theseries connections of temperature control units 7,8 and 9, respectively,with their respective thermostats. Thus, all temperature control unitsare disabled in a staggered manner.

In order to prevent the building temperature from being either too highor too low when the temperature control units 1 through 9 are disabled,temperature limit switch 90 is provided. Temperature limit switch 90 isarranged to complete an energizing path for relay 60 if the ambienttemperature of the building falls below or rises above predeterminedtemperature limits. For example, temperature limit switch 90 may be setto close the path when the building temperature drops below 45° or risesabove 95°. If either of these events occurs and temperature limit switchcompletes an energizing path for relay 60, normally closed contact pair61 opens and de-energizes heaters 11 and 12 of time delay relay 10.After a delay period, contact pairs 13, 14 and 15 close, placingtemperature control units 1,2 and 3, respectively, under the control oftheir respective thermostats. Contact pair 16 opens, de-energizingheaters 21 and 22 of time delay relay 20. After a delay period, contactpairs 23, 24 and 25 close, placing temperature control units 4,5 and 6,respectively, under the control of their respective thermostats. Contactpair 26 opens, deenergizing heaters 31 and 32 of time delay relay 30.After a delay period, contact pairs 33, 34 and 35 close, placingtemperature control units 7,8 and 9, respectively, under the control oftheir respective thermostats. The building is then either heated orcooled, as the case may be, until temperature limit switch 90 opens theenergizing path of relay 60. This opening will occur when thetemperature changes by some predetermined amount, for example threedegrees. Contact pair 61 then closes, causing the staggered energizationof time delay relays 10, 20 and 30 and the subsequent disabling oftemperature control units 1 through 9, as heretofore described. It isthus seen that whenever temperature control units 1 through 9 are eitherenabled or disabled, it is in a staggered manner so as not to create adamaging power surge.

When motor 51 moves contact 52 into engagement with OFF contact 54,power is removed from heaters 11 and 12 of time delay relay 10. Thiscauses control of temperature control units 1 through 9 to revert totheir respective thermostats in the staggered manner described above.

Override switch 80 is provided so that in the event of an unscheduledoccupancy of the building, the temperature control units 1 through 9 mayrevert to the control of their respective thermostats in order to makethe building temperature suitable for human occupancy. With timer 50 inthe ON state, if a person enters the building and desires to enable thetemperature control units 1 through 9, he or she would close overrideswitch 80. This provides an energization path for relay 60 throughnormally closed contact pair 71 of relay 70. The energization of relay60 would open normally closed contact pair 61, removing power fromheaters 11 and 12 of time delay relay 10. As described above, thiscauses the temperature control units 1 through 9 to revert to thecontrol of their respective thermostats in a staggered manner. Whenoverride switch 80 is opened, relay 60 is deenergized and time delayrelays 10, 20 and 30 operate to remove control of temperature controlunits 1 through 9 from their respective thermostats.

In the event the override switch 80 were not opened, control apparatus100 could be disabled for days until someone eventually opened switch80. To prevent this from occurring, relay 70 is provided in circuitconfiguration to bypass switch 80 the next time timer 50 goes into itsOFF state. With switch 80 closed, when contact 52 engages OFF contact54, an energization path is completed for relay 70. Relay 70 locks upthrough normally open contact pair 72 and closed switch 80. Normallyclosed contact pair 71 opens and removes switch 80 from the energizationpath of relay 60. The status of temperature control units 1 through 9remains the same, that is they are under the control of their respectivethermostats. However, the next time contact 52 engages ON contact 53,temperature control units 1 through 9 may be removed from the control oftheir respective thermostats even though switch 80 is still closed. Thisis because relay 70 remains energized and keeps open the energizationpath of relay 60 which includes switch 80. Switch 80 can have no furthereffect on control apparatus 100 until it is first opened. When thisoccurs, relay 70 is de-energized, returning normally closed contact pair71 to its closed state, thereby returning the energization of relay 60to the control of switch 80. A subsequent closure of override switch 80when timer 50 is in its OFF state will return the control of temperaturecontrol units 1 through 9 to their respective thermostats.

There has thus been described apparatus for controlling a plurality ofenergy consuming devices in a programmable and economical manner. Theapparatus is fail-safe in that in the event of a malfunction, control ofthe devices automatically reverts back to the individual devices. Thereis also the provision of a manual override capability and an automaticdisabling of this capability.

Whereas this invention is herein illustrated and described with respectto a specific embodiment thereof, it should be realized that variouschanges may be made without departing from the essential contributionsto the art made by the teachings hereof.

I claim:
 1. Apparatus for controlling a plurality of devices to bealternately enabled and disabled during predetermined cyclicallyrecurring time periods including: two state programmable timer meansarranged to be in a first of its states during those of said timeperiods when said plurality of devices are to be enabled and in thesecond of its states during those of said time periods when saidplurality of devices are to be disabled; a plurality of bistableelements connected in chain-like configuration to said timer means so asto sequentially switch in a predetermined order from their first statesto their second states responsive to said timer means changing from itsfirst state to its second state and to sequentially switch in saidpredetermined order from their second states to their first statesresponsive to said timer means changing from its second state to itsfirst state, said bistable elements including delay means so that thesequential switching is spread out over a predetermined period of time;switch means operatively connecting said plurality of devices torespective ones of said plurality of bistable elements so as to enableeach of said devices when its respective bistable element is in itsfirst state and to disable each of said devices when its respectivebistable element is in its second state; manually operable overrideswitch means for providing an indication that said devices are to beenabled; override enabling means connected to said override switch meansand responsive to said indication for switching said bistable elementsto their first states; override disabling means interposed between saidoverride switch means and said override enabling means, said overridedisabling means being responsive to said indication from said overrideswitch means and to said timer means changing to its first state foropening the connection between said override switch means and saidoverride enabling means, and said override disabling means being furtherresponsive to a subsequent termination of said indication from saidoverride switch means for closing the connection between said overrideswitch means and said override enabling means.
 2. The apparatus of claim1, wherein said devices are thermostatically responsive temperaturecontrol units including control wires connecting each of said units to arespective thermostat through said switch means and said switch means isarranged to disconnect respective thermostats from respective units whenthe respective bistable elements are in their second state and toconnect respective thermostats to respective units when the respectivebistable elements are in their first state.
 3. The apparatus of claim 2,further including: temperature limit switch means providing anindication of a temperature outside a predetermined range; and meansresponsive to said indication for switching said bistable elements totheir first states.
 4. Apparatus for controlling a plurality of devicesto be alternately enabled and disabled during predetermined cyclicallyrecurring time periods including: two state programmable timer meansarranged to be in a first of its states during those of said timeperiods when said plurality of devices are to be enabled and in thesecond of its states during those of said time periods when saidplurality of devices are to be disabled; a plurality of bistableelements connected in chain-like configuration to said timer means so asto sequentially switch in a predetermined order from their first statesto their second states responsive to said timer means changing from itsfirst state to its second state and to sequentially switch in saidpredetermined order from their second states to their first statesresponsive to said timer means changing from its second state to itsfirst state, said bistable elements including delay means so that thesequential switching is spread out over a predetermined period of time;and switch means operatively connecting said plurality of devices torespective ones of said plurality of bistable elements so as to enableeach of said devices when its respective bistable element is in itsfirst state and to disable each of said devices when its respectivebistable element is in its second state; said bistable elementscomprising time delay relays and said switch means comprising normallyclosed contact pairs of respective ones of said time delay relays. 5.Apparatus for enabling and disabling the thermostatic control of aplurality of building temperature control units according to apredetermined and programmable cyclically recurring schedule including:a programmable timer providing a signal along a first path during timeperiods of enablement and along a second path during time periods ofdisablement; and a plurality of time delay relays each having a slowacting energization element and a plurality of normally closed contactpairs, the thermostat control wires of each of said temperature controlunits being serially connected to a respective one of said normallyclosed contact pairs, the energization element of a first of said timedelay relays being connected to said second path, said first time delayrelay having a normally open contact pair connected to an energizationpath for a second of said time delay relays, said second time delayrelay having a normally open contact pair connected to an energizationpath for a third of said time delay relays, etc., whereby theenergization or de-energization of said first time delay relay causes asequential and staggered energization or de-energization, respectively,of said plurality of time delay relays and a corresponding disablementor enablement, respectively, of the thermostatic control of saidplurality of temperature control devices; a first relay having anormally closed contact pair serially connected in said second path; anda temperature limit switch serially connected to the energizationelement of said first relay, said temperature limit switch closing whenthe building temperature varies outside a predetermined range.
 6. Theapparatus of claim 5, further including a manually operable overrideswitch serially connected to said energization element of said firstrelay in a path parallel to said temperature limit switch.
 7. Theapparatus of claim 6, further including a second relay having a normallyclosed contact pair serially connected between said override switch andthe energization element of said first relay, the energization elementof said second relay being serially connected between said first pathand said override switch, said second relay having a normally opencontact pair connected to lock, in an energized state, said second relayuntil said override switch is opened.